In the context of saving power:
the RPi cannot turn itself OFF - at least not completely
the RPi cannot turn itself ON - this requires external intervention
viewed as a ROI question, consider the cost of running RPi 24x7x365 is less than £5 per year
Using cron - and only cron, here's what you can do to save power:
Scheduling a shutdown will help ensure ...
If it were me, I would get a cheap RPi zero W or just zero, or even the new rPi Pico and wire a micro USB to a PCB or breadboard with an NPN 2n2222 transistor and have it give power from the time a to time b and off otherwise. Then you have a handy little IOT switch and since you are not using mains power you can use just a transistor instead of a relay. But ...
If they are both inputs they will have random voltages (randomly high or low).
If they are both outputs they will either be both high, both low, or one high one low (a recipe for damage).
If one is an input and the other is an output the input will have the voltage set at the output.
The "one button ON-OFF" switch function has been built into the Raspberry Pi device tree since July, 2017. All that's really required is two pieces of wire, but a momentary push-button switch can be added if you wish - perhaps your "three pin switch" can serve in this role?
Let me explain in the following schematic what is ...
Your question is vague and lacking direction and you have given no details about the software you are running or what the cluster does, but let's see if we can enumerate the possibilities. Will powering down the switch impact the cluster? Here's a list of possible ways it could impact it:
Hardware: ethernet is designed to be disconnected while powered on. ...
Maybe? It will not damage the hardware which has been designed to tolerate that. As far as software that is an entirely different arena and is dependent on the programs themselves. Some may just sit there and come back when the switch comes back up, some may hang, and some may just shut down. I have no way of knowing as I have no idea of what programs (tasks)...